new Promise(resolve => {
	setTimeout(() => {
		const a = 'hello'
		resolve(a)
	}, 10)
}).then(v => {
	return new Promise(resolve => {
		setTimeout(() => {
			const b = 'lagou'
			resolve(v + b)
		}, 10)
	})
}).then(v => {
	setTimeout(() => {
		const c = 'I ❤ U'
		console.log(v + c)
	}, 10)
})